It's close. Based on the experience and being the one to get the Golden goal in 2010, Sid should get the nod. Besides the fact that he's been the long-time captain of a perennial playoff team has won a cup, he's seen it all firsthand and was not to be denied in the clutch. Without that golden goal though, I would go with Toews.
However if Niedermayer were still around, he would be the obvious choice. Gold winning captain > Golden goal scorer.